On Wed, Jan 25, 2017 at 10:29 PM, Matt Corallo via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> To maximize fork divergence, it might make sense to require this. Any
> sensible proposal for a hard fork would include a change to the sighash
> anyway, so might as well make it required, no?
>

Compatibility with existing transaction-signing software and hardware
should be considered.

I think any hard fork proposal should support a reasonable number of
reasonable-size old-sighash transactions, to allow a smooth transaction of
wallet software and hardware and to support anybody who might have a
hardware wallet locked away in a safe deposit box for years.

-- 
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Gavin Andresen